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玛氏宠物护理学院

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Science Head

科研主管

 

Dr Abigail Stevenson has over 10 years experience working in the area of feline and canine urinary tract health. The title of her PhD thesis was ‘The incidence of urolithiasis in cats and dogs and the role of nutrition in formation and prevention of recurrence’. Abigail is passionate about this area of science and has shared her knowledge via peer reviewed publications and presentations at key conferences. Abigail is also a pet lover and a proud owner of 2 dogs (a Jack Russell terrier and a Dogue de Bordeaux), 1 cat and 4 horses.
Abigail Stevenson博士在猫科与犬科尿道健康领域已经有超过10年的工作经验。Abigail Stevenson的博士论文题目为“猫狗尿石症的发病率以及尿石症再复发形成与预防过程中营养素的作用”。Abigail对该领域的研究充满热情,经常通过同行评审期刊以及在重要会议发言的方式与业界分享其丰富的知识见解。Abigail同时也是一位宠物爱好者,目前自己养育2只宠物狗(一只杰克罗素梗犬与法国波尔多犬)、1只猫和4匹马。

 

Key Message

关键信息

WALTHAM has contributed to the understanding of urinary tract health in cats through:

通过以下方式,威豪成功地促进了对猫尿道健康领域的理解:

  • Development of novel methodologies for urine collection and analysis.

  • Demonstrating that a diet producing moderately acidic urine can minimise the risk of both calcium oxalate and struvite formation in cats.

  • Demonstrating that increasing water intake results in urinary dilution that is beneficial for urinary tract health in cats.

  • Generating insights that indicate that feeding patterns can influence the 24-hour urine pH profile; and that the age of the cat may be a factor influencing urolith type.

  • 开发出尿液收集与分析的新方法;

  • 证明食用有助于促进中度酸性尿生成的饮食能够最大程度地降低猫体内草酸钙与鸟粪石的形成几率;

  • 证明增加水的摄入能够促进尿液的稀释,从而有利于猫的尿道健康;

  • 促使人们形成以下见解:喂食方式能够影响猫的24小时尿液pH值状况;猫的年龄可能是尿石类型的影响因素之一。

 

Background

背景

Feline lower urinary tract diseases (FLUTD) are characterised by haematuria (blood in the urine), dysuria (painful urination), inappropriate urination, stranguria (the urge to urinate), pollakiuria (frequent urination) and sometimes urethral obstruction (which can rapidly become fatal).

猫下泌尿道疾病(FLUTD)的特征包括血尿症(尿液中有血)、排尿困难(排尿疼痛)、乱尿、痛性尿淋沥(排尿感强烈)、尿频(频繁排尿)以及(有时候)尿道阻塞(具有迅速致命性)。

Urological diseases are a common reason for veterinary hospital admissions, involving over 7% of the feline case load (Osborne et al. 1995). One study examining obstructed cats found that 60.4% presented with urethral plug, 11.3% with uroliths and, in the remaining 28.3%, no cause could be found (Osborne et al. 1989). A study in non-obstructed cats reported that 15% of urological cases presented with urolithiasis and other causes of the disease included anatomical abnormalities (11%) and behavioural problems (9%), with idiopathic cystitis diagnosed in 64% (Buffington et al. 1997).

泌尿外科疾病是动物进入兽医院治疗的一个常见原因,其中,猫的病例数量约占泌尿外科疾病入院动物病例的7%以上(Osborne 等,1995年)。一项针对发生尿路阻塞的猫的研究发现,60.4%由尿道栓子所导致,11.3%由尿石所导致,其余28.3%的病例尚未确定发病原因(Osborne等,1989年)。一项对未发生尿路阻塞的猫的研究结果表明,在这些猫的病例中,15%患有尿石症,其他泌尿系统疾病病因包括解剖学异常(11%)、行动问题(9%)以及自发性膀胱炎(64%)(Buffington等,1997年)。

 

Urolithiasis

尿石症

Urolithiasis can be defined as formation of sediment anywhere within the urinary tract consisting of one or more poorly soluble crystalloids of urine. The condition starts with the formation of urinary crystals that may, in the right conditions, progress to form uroliths (stones) within the urinary tract. Uroliths are most commonly found in the bladder although kidney uroliths have also been diagnosed but to a far lesser extent. Uroliths form when specific minerals or compounds in supersaturated urine precipitate, and the crystals coagulate and grow.

尿结石是指在尿道中某处形成的由一种或多种难溶性尿液晶体所组成的沉淀物。该疾病的症状从尿结晶形成开始,尿结晶在一定的条件下可以在尿道中发展成为尿石(结石)。尽管肾脏结石也会被诊断出来,但最常见的结石仍然是膀胱结石(前者的频率远低于后者)。在过度饱和状态下,尿液中某些矿物质或化合物就会沉淀为晶体,然后不断凝结和增大, 最后就会形成尿石。

Factors influencing urolithiasis include the concentration of the solutes (Figure 1), urine pH, urine temperature, genetic or metabolic disorders, lifestyle and body condition, and the presence or absence of various promoters (such as bacteria) and inhibitory factors (such as citrate and pyrophosphate).

尿石症的影响因素包括溶质浓度(图1)、尿液pH值、尿液温度、遗传性或代谢性疾病、生活方式与身体状况、各种启动子(如细菌)的存在与缺失以及各种抑制因素(如柠檬酸盐与焦磷酸盐)。

Reproduced from Markwell PJ, Buffington CT, Smith BH. The effect of diet on lower urinary tract diseases in cats. J Nut. 1998 Dec;128(12Supp):2753S-2757S

摘自“饮食对猫的下尿道疾病的影响”;作者:Markwell PJ, Buffington CT, Smith BH.;《营养杂志》1998年12月期刊;128(12月增刊):2753S-2757S

 

Figure 1: Some solutes affecting crystallisation in urine (Markwell et al. 1998). Other factors affecting crystal formation include time, temperature, and the presence, absence, and effectiveness of endogenous protein crystallisation inhibitors

图1: 尿液中影响结晶的部分溶质(Markwell 等,1998年)。其他影响晶体形成的因素包括时间、温度以及内源性蛋白质结晶抑制剂的存在、缺失与影响等。

Although urinary crystals are frequently associated with the clinical signs of FLUTD, the presence of crystals in urine does not itself cause disease, and crystalluria can occur in healthy cats that never go on to develop FLUTD. However, implementing strategies that help prevent crystal formation will greatly reduce the risk of urolithiasis and the formation of the mineral component of urethral plugs.

The most common uroliths in cats are composed of struvite (magnesium ammonium phosphate) or calcium oxalate (Markwell et al. 2000; Rogers et al. 2011).

尽管尿结晶经常会导致猫出现下泌尿系疾病,但尿液中存在的结晶本身并不会导致这种疾病,晶尿症也会发生在从未患上下泌尿系疾病的健康猫的身上。然而,实施有助于防止晶体形成的策略能够在很大程度上降低尿石症的风险,也有助于防止尿道栓子中矿物成分的形成。

猫最常见的尿石是鸟粪石(磷酸铵镁)或草酸钙(Markwell等,2000年;Rogers等,2011)。

Struvite

鸟粪石

This was the most common urolith type found in cats during the 1980s and has recently returned to being the most prevalent urolith (Osborne et al. 2009). Consequently there is considerable literature documenting risk factors and prevention strategies. Struvite can occur at any age and is more common in female cats. Unlike dogs and humans, most feline struvite uroliths tend to form in sterile urine (Houston and Elliott 2008). Controlling urine pH is critical for the management and prevention of struvite as alkaline urine increases the risk of struvite crystallisation and subsequent urolith formation. Increasing urine volume is also important since this will dilute urinary minerals. Although relatively less important than controlling urine pH, levels of dietary minerals (magnesium and phosphorus) may also be important. Examples of struvite crystals (Figure 2) and a struvite urolith (Figure 3) are shown below.

在20世纪80年代,鸟粪石是猫最常见的尿石类型,最近,这种疾病又重新成为最流行的尿石疾病(Osborne等,2009年)。因此,关于鸟粪石方面风险因子与预防策略方面的文献数量较多。任何年龄的猫均可能患上鸟粪石,但母猫更容易患上该疾病。与狗和人类不同,大多数猫的鸟粪石往往在无菌尿液中形成(Houston 与 Elliott, 2008年)。由于碱性尿液能够增加鸟粪石结晶以及随后转化为尿石症的风险,因此控制尿液pH值对于鸟粪石的管理与预防具有至关重要的意义。尿液能够稀释尿液中的矿物质,因此增加尿液量也具有重要意义。尽管饮食中的矿物质(镁与磷)含量相对于尿液pH值控制的重要性相对较低,但仍不失其重要性。鸟粪石晶体(图2)与鸟粪石尿石(图3)的实例如下图所示。

Figure 2: Struvite crystals

图2鸟粪石晶体

 

Figure 3: 100% struvite urolith – female cat, 5 years of age

3:100%鸟粪石尿石——母猫(5岁)

Calcium oxalate

草酸钙

The incidence of this urolith type appeared to increase through the 1980s and 1990s, making up only 2% of uroliths analysed in 1981 but increasing to 55% by 2002 (Osborne et al. 2009). However, by 2007 calcium oxalate occurrence had decreased back to 41% of uroliths submitted for analysis (Osborne et al. 2009). Calcium oxalate is more commonly found in middle aged (mean age 7.8 years), male cats (Houston and Elliott 2008). Increasing water intake resulting in urinary dilution is an important part of reducing the risk of calcium oxalate formation. The role of urine pH in calcium oxalate formation is more controversial. The influence of urine pH on calcium oxalate solubility is low across the physiological pH range and urine pH is a poor predictor of the risk of calcium oxalate formation (Houston and Elliott 2008). Examples of calcium oxalate crystals (Figure 4) and uroliths (Figure 5) are shown below.

草酸钙型尿石的发生率似乎在上个世纪80与90年代呈现增加的趋势——1981年,草酸钙尿石症的发生率仅占尿石症总数的2%,但这一数字在2002年迅速上升至55%(Osborne等,2009年)。然而,在随后的2007年,送交分析草酸钙鸟粪石病例比例回降至41%(Osborne等,2009年)。草酸钙更常见于中年猫(平均年龄7.8岁)和雄猫(Houston与Elliott, 2008年)。增加水的摄取量能够促进尿液稀释,因此对于降低草酸钙在体内的形成具有重要意义。尿液的pH值在草酸钙形成过程中的作用则更富争议。在生理学的pH值范围内,尿液的pH值对草酸钙溶解度的影响较低,因此尿液pH值在作为预测草酸钙形成风险方面的作用较差(Houston与Elliott, 2008年)。草酸钙晶体(图4)与草酸钙尿石(图5)实例如下图所示。

Figure 4: Calcium oxalate crystals

图4草酸钙晶体

 

Figure 5: 100% calcium oxalate uroliths – male cat, 9 years of age, neutered

图5:100%草酸钙尿石——阉割母猫(9岁)

 

Urolithiasis and the role of nutrition

尿石症与营养素的作用

It is possible to influence at least some of the risk factors associated with the two most common urolith types through diet and feeding regimen. Dietary ingredients and feeding patterns can influence the volume, pH, and solute concentration of the urine (Markwell et al. 1998). Diet can also influence water balance. Cats being fed dry cat food often produce smaller volumes of more concentrated urine (Markwell et al. 1999a), probably because they take in less total water (Burger et al. 1980).

饮食与喂食方法至少能够对导致两种最常见类型的尿石症风险因子产生影响作用。饮食成分与喂养方式能够影响尿液的数量、pH值以及溶质浓度(Markwell等,1998年)。饮食还能够影响猫体内的水平衡状态。被喂食干性猫粮的猫的尿液量往往较低,而且浓度较高(Markwell 等,1999年a),这很可能是因为这些猫的水摄入总量较低的缘故(Burger 等,1980年)。

Diet can positively impact on the urinary tract health of cats in two ways:

饮食能够通过以下两种方式对猫的尿道健康产生积极影响:

  1. Therapeutic diets that support the veterinary care of clinical cases with struvite and calcium oxalate urolithiasis. WALTHAM was first to demonstrate that it is possible to formulate a diet that will produce moderately acidic urine that is undersaturated for both struvite and calcium oxalate, thus treating the two most common stone types with one diet. Under these conditions existing struvite uroliths may also be dissolved (Houston et al. 2004) although existing calcium oxalate uroliths must be surgically removed.  

  2. Diets that reduce the risk of struvite and calcium oxalate formation in healthy cats. Diets formulated to produce urine within the metastable zone of saturation will help maintain urinary tract health in healthy cats.

1. 对患有鸟粪石与草酸钙尿石症的猫的临床兽医护理具有支持作用的治疗饮食。作为宠物护理机构,威豪第一个证明在制备能够促使猫产生鸟粪石与草酸钙含量均处于非饱和状态的中性酸性尿液的猫粮方面具有可能性,进而使采用同一种猫粮治疗上述两种最常见的结石疾病成为现实。采用上述治疗饮食可以使已经生成的鸟粪石结石溶解(Houston等,2004年),但已经生成的草酸钙结石仍必须通过手术予以清除。

2. 能够降低健康猫体内形成鸟粪石与草酸钙风险的饮食。有助于猫产生处于饱和介稳区的尿液的猫粮有助于促进健康猫的尿道健康。

Why WALTHAM is Interested

为何威豪有兴趣从事该领域的研究

Urolithiasis is an important lower urinary tract disease in cats (Markwell et al. 1998) that can be modulated through diet. It is important to understand the impact of dietary components such as minerals and moisture content on struvite and calcium oxalate urolith formation in order to help develop diets that reduce the risk or aid in the management of this disease.

尿石症是一种主要的可以通过饮食进行调节的猫下泌尿道疾病(Markwell等,1998年)。了解饮食成分(如矿物质与水分含量) 对鸟粪石与草酸钙尿石形成的影响具有重要意义,这有助于开发出能够降低尿石症发病风险或帮助对上述疾病进行管理的猫粮。

Approach

方法

For studies investigating the influence of nutrition on the risk of urolithiasis an ethical method of urine collection was required that allowed repeated assessment of naturally voided urine. This methodology allows constant urine pH monitoring and relative supersaturation assessment, critical for establishing the influence of diet on the risk of struvite and calcium oxalate formation.

以考察营养素对尿石症风险的影响为目标的研究,要求研究人员采用符合医学伦理的方法收集尿液,并能够对自然排泄的尿液进行重复性评估。该方法能够对尿液剂型持续pH值监测与相对过度饱和度评估,因此对于确定猫粮对于鸟粪石与草酸钙的形成风险具有关键性意义。

Key areas of investigation within this programme include the influence of urinary pH on the risk of urolith formation and the benefits of increasing moisture intake, through feeding wet foods or through dietary sodium manipulation as a way of encouraging cats to drink more.

该研究项目的关键研究领域包括尿液pH值对尿石形成的风险的影响程度以及通过喂食湿性猫粮或通过调控饮食中的钠含量使猫多饮水的方法提高猫的水分摄入量的相关益处。

Capability Development

能力开发

In order to investigate urinary tract health, WALTHAM developed a novel methodology for collecting urine samples from cats, enabling pH monitoring and relative supersaturation (RSS) assessment

为了研究猫的尿道健康,威豪开发出一种新方法用于收集猫的尿液样本,从而使尿液pH值监测和相对过饱和度评估成为可能。

A system was developed to collect naturally voided urine samples (Markwell and Smith 1993). When the cats at WALTHAM are participating in studies, they may be housed individually in purpose-built lodges. The litter trays are designed with a sloped base so that urine rapidly drains through a hole in one corner into a collection bottle beneath. The cats are readily trained to use these litter trays by gradually reducing the amount of litter over a period of weeks until the cat is happy to urinate directly onto the sloping tray. This set-up allows the non-invasive collection of urine samples. It can also be modified to freeze the urine as soon as it is voided to enable RSS assessment.

研究人员已经开发出一套用于收集自然排泄尿液样本的系统(Markwell与Smith,1993年)。在参加相关研究过程中,威豪宠物中心的猫可以选择单独住在特别设计的猫窝中。猫砂盘经过特殊设计,底部呈斜面形,从而使尿液可以通过位于边角处的小孔流入安装于下方的尿液收集瓶中。工作人员对猫进行训练使其熟练使用猫砂盘,具体方式是在一周多的时间内逐渐缩小猫砂盘的大小从而最终使猫愿意直接在倾斜底面上排尿。这一设计使得工作人员可以采用非侵入方式收集到猫的尿液样本。通过一定的修改,该方法还可以对排泄后的尿液进行迅速冷冻,从而对其进行相对过度饱和度评估。

Urine pH monitoring

尿液pH值监测

In order to monitor pH, urine passes through a purpose built glass U-tube containing a temperature/pH probe over which urine passes on its way to the collection bottle (Markwell and Smith 1993). The pH probes are connected via pH meters to a computer to log the data (Figure 6). A rise in temperature signals urination and triggers data capture.

为了监测尿液pH值,研究人员需要使尿液通过特殊设计的U型玻璃试管,试管中装有温度/pH值探测器,尿液在流经探测器之后进入尿液收集瓶(Markwell与 Smith,1993年)。该pH值探测器通过pH计与电脑相连以记录相关数据(图6)。如果检测到温度升高,则表示猫在排尿,此时系统就会自动进行数据采集。

This system has advantages over traditional alternatives such as cystocentisis because it is non-invasive, does not interfere with the cat’s normal urination patterns and allows the rapid and repeated analysis of pH without storage delays.

由于该系统系非侵入性检测法,不会对猫的正常排尿方式形成干扰,而且允许研究人员能够对猫的尿液pH值进行快速、重复分析而不会因为贮存延误检测时间,因此相对于传统尿样采集方法(如穿刺法),该系统具有多种优点。

Figure 6: Schematic diagram of the WALTHAM system for monitoring urine pH in cats

图6:威豪的猫尿液pH值监测系统示意图

Relative Supersaturation

相对过饱和度

Relative supersaturation (RSS) assessment has been regarded as the gold-standard in the human field for decades. However, its adaptation for predicting the crystallisation potential of cat urine is much more recent. WALTHAM utilised the urine collection system initially used for urine pH assessment (Markwell and Smith 1993) and modified it to collect urine samples for RSS assessment in cats (Markwell et al. 1999b).

几十年以来,相对饱和评估一直被认为是人类泌尿系统结石诊断的金标准。然而,将相对饱和评估用于预测猫的尿液结晶形成的可能性却是近期才采用的方法。威豪宠物中心从一开始就采用尿液收集系统进行尿液pH值评估(Markwell与Smith, 1993年),并将对该系统进行修改以用于收集猫的尿液样本并进行相对过饱和度评估(Markwell等,1999b)。

In collaboration with Dr WG Robertson, a world-leading human urologist at University College London, WALTHAM researchers validated the methodology for measurement of RSS of cat urine (Robertson et al. 2002). Two programs (SUPERSAT and EQUIL2) were evaluated as to their suitability for calculating calcium oxalate and struvite RSS in cat urine (Robertson et al. 2002). EQUIL2 and SUPERSAT both calculated reasonably accurate RSS values for calcium oxalate in cat urine, whereas only SUPERSAT provided an accurate measure of struvite RSS (Robertson et al. 2002). This study suggests that, for cat urine, SUPERSAT is the most accurate and repeatable method for calculating RSS.

通过与WG Robertson医生(英国伦敦大学学院国际著名人类泌尿专家)合作,威豪的研究人员对猫的尿液相对过饱和度测量方法进行了验证(Robertson等,2002年)。研究人员还对SUPERSAT与QUIL2两种程序在计算猫的尿液中草酸钙与鸟粪石相对过饱和度的适用性进行了评估(Robertson等,2002年)。这两个项目均能够对猫尿液中的草酸钙的相对过饱和度进行合理与准确的计算,但只有SUPERSAT项目能够对鸟粪石的相对过饱和度进行准确测量(Robertson 等,2002)。该研究表明,在猫的尿液测量方面,SUPERSAT是测量相对过饱和度方面的最准确的可重复性方法。

Accurate RSS measurement and interpretation underpins the feline urinary tract health research programme at WALTHAM. All researchers in the field agree that urine has to be over(super)saturated with at least one stone-forming mineral for uroliths to form. RSS falls within three definable zones of relative supersaturation (Figure 7 Houston and Elliott 2008).

对相对过饱和度进行准确的测定与解释是威豪猫尿道健康研究项目的基础。所有该领域的研究人员均认为,只有在尿液中至少存在一种能够形成尿石的超(过)饱和状态矿物质的条件下,尿石才可能形成。相对过饱和度的三种可定义状态如下图所示(图7: Houston 与 Elliott, 2008年)

 

Reproduced from Houston DM, Elliott DA. Nutritional management of feline lower urinary tract disorders. In: Encyclopedia of Feline Clinical Nutrition. Eds: Pibot P, Biourge V, Elliott D.2008.Aniwa SAS, France. Pages 285-322

摘自Houston DM与 Elliott DA的“猫下泌尿道疾病的营养管理”。选自:猫的临床营养学百科全书。编辑:Pibot P, Biourge V, Elliott D,2008年,法国Aniwa SAS期刊,第285-322页

Figure 7: Zones of urinary relative supersaturation and the crystallisation processes that occur in each zone (Houston and Elliott 2008)

图7尿液相对过饱和度状态与各状态的结晶过程(Houston 与Elliott, 2008年)

Zone of undersaturation

欠饱和状态

Any crystals added to urine in this state will dissolve. If urine is maintained within this zone uroliths cannot form.

向处于欠饱和状态的尿液加入的任何晶体均会被溶解。如果尿液一直能够保持在这一状态,则尿石永远不会形成。

Zone of metastable supersaturation

亚稳过饱和状态

Urine of normal healthy subjects is often in this zone and crystals can be passed with no harm. As the level of metastable saturation approaches the formation product the length of time before crystallisation commences is reduced. The time between urine formation and crystallisation may also be shortened by the presence of nucleating material such as cell debris or crystals of other mineral types. Any pre-existing crystals are likely to grow in the metastable zone.

正常、健康的试验对象的尿液往往处于亚稳过饱和状态,晶体可以通过该种尿液排出且不会造成任何伤害。由于亚稳过饱和状态的浓度接近晶体形成状态,因此晶体开始形成之前的时间相对较短。尿液形成与晶体形成之间的时间间隔可能也由于有核材料(如细胞碎片或其他矿物晶体)的存在而被缩短。而且,已经形成的晶体还可能在亚稳过饱和状态的尿液中继续生长。

Zone of oversaturation

过饱和状态

This is a highly unstable environment in which spontaneous crystal formation occurs along with crystal clumping and growth. Within this zone urolith formation is highly likely.

过饱和状态是一种高度不稳定状态。在这种状态中,晶体可以自发形成、聚集和生长。因此,在过饱和状态尿液中,鸟粪石形成的可能性非常高。

Discovery (Urinary Dilution)

发现与结论(尿液的稀释)

Dietary sodium and dietary moisture are effective strategies for urinary dilution and reducing the risk of calcium oxalate urolith formation

饮食中的钠与水分是尿液稀释的有效策略,能够有效降低尿液中草酸钙尿石的形成风险。

The simplest way of reducing RSS and therefore the risk of urolithiasis is through increasing urine volume. In humans low urine volume has been established as a risk factor for stone formation. WALTHAM investigated two approaches to increasing urine volume through increasing water intake: namely dietary sodium and dietary moisture.

尿液稀释是降低相对过饱和度最简单的方法,因此,增加尿液量有助于降低甚至消除尿石症的风险。对于人类而言,较低的尿液量已经被确定作为结石形成的风险因素之一。威豪已经成功开发出了两种通过增加水的摄入量而提高尿液量的方法:即调控饮食中的钠与水分含量。

Dietary sodium

饮食中的钠含量

Early studies showed that cats (like humans) respond to dietary sodium chloride (salt) by drinking more (Burger et al. 1980). More recently, WALTHAM assessed the effect of dietary sodium content on the water intake and urine composition of adult cats (6 in each group) fed 23 commercially-available dry diets for 21 days (Hawthorne and Markwell 2004). Cats fed diets with higher sodium content had a significantly higher water intake and urine volume, significantly lower urine specific gravity, and significantly lower RSS for calcium oxalate (Figure 8) (Hawthorne and Markwell 2004). Urine pH was not affected. These data show that, even within the range of sodium intakes provided by standard diets, those with a higher sodium content increase water intake and reduce RSS for calcium oxalate.​

早期的研究结果显示,与人类相似,饮食中的氯化钠(盐)会导致猫的饮水量增加(Burger 等,1980年)。后来,通过喂食23种商业干性猫粮的21天试验,威豪对饮食中的钠含量对成年猫(每组6只)水摄入量和尿液成分的影响进行了评估(Hawthorne与 Markwell ,2004年)。试验结果表明,喂食钠含量较高的饲粮的猫在水摄入量和排尿量方面大幅度增加,其尿液的比重以及草酸钙相对过饱和度也均显著下降(图8)(Hawthorne与Markwell, 2004年);这些猫的尿液pH值并未受到影响。上述试验数据还显示,即使在标准饮食所规定的正常钠含量范围内,钠含量相对较高的饮食也能够增加猫的水摄入量并降低其尿液中的草酸钙相对过饱和度。

 

Reproduced from Houston DM, Elliott DA. Nutritional management of feline lower urinary tract disorders. In: Encyclopedia of Feline Clinical Nutrition. Eds: Pibot P, Biourge V, Elliott D.2008.Aniwa SAS, France. Pages 285-322

摘自Houston DM与 Elliott DA的“猫下泌尿道疾病的营养管理”。选自:猫的临床营养学百科全书。编辑:Pibot P, Biourge V, Elliott D,2008年,法国Aniwa SAS期刊,第285-322页

 

Reproduced from Houston DM, Elliott DA. Nutritional management of feline lower urinary tract disorders. In: Encyclopedia of Feline Clinical Nutrition. Eds: Pibot P, Biourge V, Elliott D.2008.Aniwa SAS, France. Pages 285-322

摘自Houston DM与 Elliott DA的“猫下泌尿道疾病的营养管理”。选自:猫的临床营养学百科全书。编辑:Pibot P, Biourge V, Elliott D,2008年,法国Aniwa SAS期刊,第285-322页

 

 

Reproduced from Houston DM, Elliott DA. Nutritional management of feline lower urinary tract disorders. In: Encyclopedia of Feline Clinical Nutrition. Eds: Pibot P, Biourge V, Elliott D.2008.Aniwa SAS, France. Pages 285-322

摘自Houston DM与 Elliott DA的“猫下泌尿道疾病的营养管理”。选自:猫的临床营养学百科全书。编辑:Pibot P, Biourge V, Elliott D,2008年,法国Aniwa SAS期刊,第285-322页

 

Figure 8: The effect of dietary sodium on water intake, urine specific gravity, and calcium oxalate RSS (Houston and Elliott 2008; redrawn from Hawthorne and Markwell 2004)

图8饮食中的钠含量对水摄入量、尿液比重与草酸钙相对过饱和度的影响(作者:Houston 与Elliott, 2008年;根据Hawthorne与Markwell 于2004发表的研究成果重新绘制。)

Dietary moisture

饮食中的水分含量

In a study published in 2011 WALTHAM investigated the influence of dietary moisture content on urine parameters and total daily fluid intake in healthy adult cats using nutritionally standardised diets that varied only in moisture content (Buckley et al. 2011). In this study, 6 adult cats were fed a dry diet hydrated to 6.3%, 25.4%, 53.2% or 73.3% moisture in a randomised block crossover design. Cats fed the highest moisture diet produced urine with a lower specific gravity than the other three diets indicating a urinary dilution effect (Buckley et al. 2011). Calcium oxalate RSS was significantly lower in cats fed this diet when compared with the 6.3% moisture diet. Total fluid intake (combined dietary and voluntarily drunk water) was also significantly increased in cats fed the high moisture diet. The 73.3% diet resulted in a significantly higher total daily fluid intake (Figure 11), and production of more dilute urine with a lower risk of calcium oxalate urolith formation when compared to a low moisture diet (Buckley et al. 2011).

2011年,威豪公布了对饮食水分含量方面的研究成果。在该项研究中,威豪对饮食中水分含量对喂食标准化营养猫粮的健康成年猫的尿液参数及每日液体总摄入量的影响进行了研究;试验所采用的猫粮仅在水分含量方面有所差别 (Buckley等,2011年) 。在该项随机区组、交叉设计试验中,研究人员向6只成年猫喂食加入水分量分别为6.3%, 25.4%, 53.2% 或73.3%的干性猫粮。试验结果显示,喂食水分含量最高的猫粮的猫的尿液比重低于喂食其他三种水分含量猫粮的猫的尿液比重,从而表明,猫粮中的含水量对猫的尿液具有稀释作用(Buckley等,2011年);同时,喂食水分含量最高猫粮的猫的尿液中草酸钙相对过饱和程度也显著低于喂食水分含量为6.3%的猫粮的猫;此外,喂食水分含量最高的猫粮的猫在液体总摄入量(饮食中的水分与自发饮水量的总和)方面也显著增加。如图11所示,与其他喂食水分含量较低的猫粮的猫相比,喂食水分含量为73.3%的猫粮的猫在每日液体总数量方面也显著较高,因此产生的稀释尿量也较多,从而降低了尿液中草酸钙尿石形成的风险(Buckley等,2011年)。

 

Reproduced from Buckley CMF, Hawthorne A, Colyer A, Stevenson AE. Effect of dietary water intake on urinary output, specific gravity and relative supersaturation for calcium oxalate and struvite in the cat. Br J Nut 2011 S128-S130 查看
摘自Buckley CMF、Hawthorne A、Colyer A与Stevenson AE的“饮食中摄水量对猫的尿排出量、比重与草酸钙和鸟粪石相对过饱和度的影响”。选自:英国《营养学杂志》S128-S130。

Figure 9: Effect of dietary moisture on total water intake (Buckley et al. 2011). Values are means with 95% CI represented by vertical bars. Different letter indicates significant difference

9饮食中水分含量对总摄水量的影响(Buckley等,2011年)。图中各值均为在95%置信区间(以竖线表示)条件下的平均值;不同的字母表示差异程度显著。

 

Discovery (One Diet: Two Urolith Types)

One diet can be used to minimise the risk of both struvite and calcium oxalate formation in cats

发现与结论(一种饮食:两种尿石类型)

饮食可以降低猫尿液中鸟粪石与草酸钙形成的风险

Urinary acidification has long been established as a suitable approach for managing and minimising struvite formation in cats. The effect of urine pH on calcium oxalate formation is more controversial and dietary methods for managing calcium oxalate formation were poorly understood.

尿液酸化在很早之前就已经被确定为猫的鸟粪石形成预防与管理的有效方法。但尿液pH值对草酸钙型成的影响则更富有争议,而人们对通过饮食方法控制草酸钙形成的理解程度仍然较低。

In an initial study, 6 adult cats were fed an acidifying, high moisture, relatively low magnesium diet for 10 days and urine collected for 48 hours in the second week (Smith et al. 1995). This diet produced urine undersaturated with struvite and calcium oxalate in all cats (Smith et al. 1995). The overall mean urine pH was 6.23 ± 0.42 (Smith et al. 1995). Mean relative supersaturation was 0.17 ± 0.13 for struvite and 0.36 ± 0.23 for calcium oxalate (Smith et al. 1995). This study was the first indication that it was possible to formulate a diet that produced moderately acidic urine understaurated for calcium oxalate and struvite.

在一项早期试验中,研究人员向6只成年猫喂食酸性、水分含量高而锰含量相对较低的猫粮,喂食期为10天,并在试验的第二周在48小时内收集试验猫的尿液(Smith等, 1995年)。试验结果发现,该猫粮能够使所有的猫均产生鸟粪石与草酸钙处于欠饱和状态的尿液(Smith等,1995年)。试验猫的尿液pH值总平均值为6.23 ± 0.42(Smith等, 1995年);鸟粪石与草酸钙相对过饱和度平均值分别为0.17 ± 0.13与0.36 ± 0.23。该试验首次证明,制备出能够使猫产生草酸钙与鸟粪石处于欠饱和状态的中度酸性尿液的猫粮具有可能性。

Subsequently, the effect of dietary acid load on urine pH and relative supersaturation of calcium oxalate and struvite was investigated in healthy cats. Six adult cats were fed three diets in a latin square design: a nutritionally complete canned cat food (control), the control diet plus ammonium chloride (a urinary acidifier) and the control diet plus sodium bicarbonate (a urinary alkaliniser) (Stevenson et al. 2000). The control diet produced moderately acidic urine that was undersaturated for both calcium oxalate and struvite. Addition of sodium bicarbonate resulted in a significantly higher urine pH with an increased risk of struvite formation (Table 1). Addition of ammonium chloride resulted in urine with a trend towards a more acidic pH and a significantly higher calcium oxalate risk. (Table 1)

随后,研究人员还以健康猫为对象就猫粮中的酸含量对猫尿液中的pH值水平以及草酸钙与鸟粪石的相对过饱和度进行了研究。在试验中,研究人员向6只猫分别喂食以拉丁方设计的三种猫粮:营养成分完全的灌装猫粮(对照组)、对照猫粮与氯化铵(尿酸剂)以及对照猫粮与碳酸氢钠(尿液碱化剂)(Stevenson等,2000年)。试验结果发现,对照组猫粮能够使猫产生中度酸性尿液,其中的草酸钙与鸟粪石均处于欠饱和状态;喂食添加碳酸氢钠的猫粮后,猫所产生的尿液的pH值显著较高,因而鸟粪石的形成风险也有所增加(表1);添加氯化铵的猫粮使猫的尿液pH值酸性趋向于增强,从而导致草酸钙的形成风险显著增加(表1)。

Table 1: Effect of urinary acidifier (ammonium chloride, NH4Cl) or alkaliniser (sodium bicarbonate, NaHCO3) compared with control diet (C) on RSS and urine pH; mean for 6 cats (Stevenson et al. 2000).

表1尿酸剂(氯化铵,NH4Cl)或碱化剂(碳酸氢钠,NaHCO3)对猫的尿液相对过饱和度与pH值的影响(相对于对照组猫粮(C));6只试验猫的平均值(Stevenson等,2000年)

Adapted from Stevenson AE, Wrigglesworth DJ, Markwell PJ. Urine pH and urinary relative supersaturation in healthy adult cats. Urolithiasis 2000: 9th International Symposium on urolithiasis, 13-17th February, University of Cape Town. Eds: Rodgers AL, Hibbert BE, Hess B, Khan SR, Preminger GM. 2000;2:818-820

改编自Stevenson AE、 Wrigglesworth DJ、Markwell PJ的“健康成年猫的尿液pH值与尿液相对过饱和度”。尿石症2000年:第9届尿石症国际研讨会,2000年2月13-17日,开普敦大学。编辑:

Rodgers AL、Hibbert BE、Hess B、Khan SR、Preminger GM,2000年:818-820

This study clearly demonstrates that a moderately acidic urine pH results in the lowest risk of both calcium oxalate and struvite RSS.

该试验清楚地表明,中度酸性尿(pH值)能够最大程度地降低猫尿液中草酸钙与鸟粪石相对过饱和度的发生风险。

Insight Generation

Small meals fed throughout the day maintain a more constant urine pH compared with less frequent large meals

独特见解

一天之中少食多餐比多食少餐更有助于保持稳定的尿液pH

 

Data from WALTHAM show that small meals fed throughout the day appear to maintain a more constant urine pH profile and minimise the ‘alkaline tide’ effect in cats compared to less frequent large meals (Figures 10 Markwell and Smith 1993).

威豪的数据表明,相对于多食少餐,每天保持每餐较低的进食量似乎更有助于保持尿液pH值的稳定,并能够最大程度地降低“碱潮”对猫的影响(图10,Markwell 与Smith ,1993年)。

This provides an insight into practical measures that may help maintain a consistently acidic urine pH over 24 hours, and may help support dietary management of cats at risk of struvite urolithasis. The daily calorie requirement should be delivered via small meals rather than unlimited free access which may result in increased calorie intake.

上述数据在猫的饮食量使用方法方面为人们提供了一种见解,这种见解有助于猫的酸性尿液pH值在24小时内保持稳定,也有助于对存在鸟粪石尿石发生风险的猫进行饮食管理。猫在每日的热量需求应通过少食多餐的方式予以满足,而不是采取无限制自由进食的方式摄取食物,后者可能会导致热量摄取的增加。

 

Reproduced from Markwell PJ, Smith BHE. An effective urine pH monitoring system for cats. Animal Technol.1993;44(3):239-245

摘自Markwell PJ与Smith BHE的“猫的尿液pH值有效监测系统”

《动物科技》,1993;44(3):239-245

 

Reproduced from Markwell PJ, Smith BHE. An effective urine pH monitoring system for cats. Animal Technol.1993;44(3):239-245

摘自Markwell PJ与Smith BHE的“猫的尿液pH值有效监测系统”

《动物科技》,1993;44(3):239-245

 

 

Figure 10: Normal diurnal variation in cat urine pH (Markwell and Smith 1993). The top graph shows the alkaline tide 4–6 hours postprandial following a single meal of a canned diet fed at 11.30 am. The bottom graph shows no rise in pH when cats are fed three meals a day on a dry diet designed to acidify urine

图10:猫尿液pH值的正常的每日变化(Markwell 与Smith,1993年)。顶部图显示的是在尚无11:30进食单餐罐装猫粮4-6小时后猫尿液中的碱潮状况;底部图显示,按照每日三餐的标准向猫喂食有助于酸化尿液的干性猫粮后,猫的尿液中的pH值没有上升。

Kittens produce more acidic urine than adult cats and therefore, feeding acidifying diets to young cats is not recommended

幼猫能够比成年猫产生更多的酸性尿,因此不建议向幼猫喂食酸化猫粮。

A pilot study comparing the urine pH of 8-week-old kittens with adult cats (mean age 3.7 years) fed the same commercially-available canned kitten food found that the kittens produced a significantly lower urine pH than adults (Skinner et al. 1995). By 12 weeks of age the urine pH of the kittens was similar to that of the adults. Since young cats naturally produce more acidic urine and are additionally at low risk of struvite formation, the use of acidifying diets should be avoided (Skinner et al. 1995).

一项以对比8周大幼猫和成年猫(平均年龄3.7周岁)在被喂食同样的商业灌装幼猫饲粮后的尿液pH值状况为目标的初步研究表明,幼猫所产生的尿液的pH值显著低于成年猫(Skinner等,1995年)。但12周大的幼猫的尿液pH值与成年猫的尿液pH值基本相同。由于幼猫体内能够自然生成酸度更高的尿液,从而使其在鸟粪石形成方面的风险较低,因此应避免向幼猫喂食酸化猫粮(Skinner等,1995等)。

Senior cats have a lower risk of struvite formation and a higher risk of calcium oxalate formation compared with younger adult cats

与年轻的成年猫相比,老龄猫发生鸟粪石形成的风险较低,但发生草酸钙形成的风险程度较高

A pilot study compared urine pH and RSS of senior cats (aged 10.6 ± 1.3 years) with younger adult cats (4.1 ± 1 years) (Smith et al. 1997). The study found that the older cats produced more acidic urine (6.1 ± 0.2 vs 6.4 ± 0.2) with a lower struvite RSS and a higher calcium oxalate RSS. This study indicates that age may be a factor influencing the type of urolith formed with younger cats at greater risk of struvite formation and older cats at greater risk of calcium oxalate formation.

研究人员还进行了一项以对比老龄猫(10.6 ± 1.3周岁)与年轻成年猫(4.1 ± 1周岁)的尿液pH值与相对过饱和度为目标的初步研究(Smith等,1997年)。该项研究发现,老龄猫所产生的尿液酸度高于年轻成年猫(分别为6.1 ± 0.2 与 6.4 ± 0.2),前者尿液的鸟粪石相对过饱和度低于后者,而其草酸钙相对过饱和度则高于后者。该研究表明,年龄可能是影响所形成的尿石类型的因素之一,即年轻猫的鸟粪石形成风险程度更高,而年老猫的草酸钙形成风险程度更高。

Discovery (Idiopathic Cystitis)

Diet can influence idiopathic cystitis recurrence rate

发现与结论(自发性膀胱炎)

饮食能够影响自发性膀胱炎的复发率

In collaboration with Prof Tony Buffington at the Ohio State University, WALTHAM investigated the role of diet in the management of idiopathic cystitis in cats.

通过与俄亥俄州立大学的Tony Buffington教授合作,威豪对猫的自发性膀胱炎管理过程中饮食的作用进行了研究。

Idiopathic cystitis is often the diagnosis when the cat presents with signs of FLUTD and all known underlying causes are ruled out. Signs of idiopathic cystitis may spontaneously disappear with or without treatment and often recur within weeks or months after initial presentation.

如果猫出现下泌尿道疾病,而所有其他原因却都已经排除,那么此时诊断的结果往往是该只猫患上了自发性膀胱炎。自发性膀胱炎的症状可以在治疗或未经治疗的条件下自发消除,但在初次发病后的数周或数月之后又常有复发。

In this study, 54 client-owned cats diagnosed with idiopathic cystitis were fed a commercially-available acidifying diet, either as the canned or dry formulation, for up to 12 months (Markwell et al. 1999a). During that time the cats underwent repeated clinical examination and urinalysis. The proportion of cats with recurrence of lower urinary tract disease was significantly less in those fed the canned diet (11%) compared with the dry formulation (39%) (Markwell et al. 1999a). Recurrence rates of cats on the dry formulation were similar to those reported in studies examining other treatment regimens.

在该研究中,研究人员对客户的54只已经确诊患有自发性膀胱炎的宠物猫喂食商业酸化猫粮(灌装或干性剂型),喂食期为12个月(Markwell等,1999a)。在试验过程中,研究人员不断对猫进行重复性临床检查与验尿。试验发现,喂食灌装猫粮的猫出现下泌尿道疾病复发的比例(11%)显著低于喂食干性猫粮的猫(39%)(Markwell等,1999a)。被喂食干性猫粮的猫的下泌尿道疾病复发率与其他试验所报告的被实施其他饮食疗法的猫的下泌尿道疾病复发率基本相同。

Thus, the canned diet appeared to reduce the recurrence rate of cats suffering from idiopathic cystitis. The reason for this reduction has not yet been established. However, it is likely to be a consequence of a higher moisture intake that resulted in production of more dilute urine (Markwell et al. 1999a).

因此,灌装猫粮似乎有助于降低患有自发性膀胱炎的猫的发病率。尽管这一作用的原因目前尚未得以确定,但有研究人员认为,灌装猫粮的水分含量相对较高,从而使猫产生更多的稀释尿,这可能正是灌装猫粮能够降低自发性膀胱炎发病率的原因(Markwell等,1999a)。

 

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